Connecting classification with phylogeny

Connecting classification with phylogeny


Using phylogeny to trace the relatives of birds


Anatomy of a phylogenetic tree


How to draw phylogenies: branch shape and length

How to draw phylogenies: branch shape and length

Mapping traits on a tree

- Critical innovations: Derived traits
- adaptive traits that define new taxa
- marked with ‘slashes’ on tree
- ‘shared derived character’ in book


Convergent evolution in marine mammals (analogous traits)


How to use derived characters to infer phylogeny

Let’s draw it

- Parsimony = Simplest solution is the likely path of evolution
- A logical way to identify homologous and analogous traits
- Minimize the # of evolutionary changes needed to explain your character data
How to draw a phylogeny…


Whale Evolution: A Case History
- Phylogenetic trees based on morphology place whales outside of the artiodactyl group
- Atiodactyl: mammals - cows, deer and hippos
- hooves, even number of toes
- unusual pulley-shaped ankle bone
- Astragalus ankle bone is a synapomorphy (shared derived trait) shared by all artiodactyls

Whale Evolution: A Case History
- How do we determine evol’n relationships?
- morphology - presence/absence of weird ankle bone
- DNA sequences - shared gene families
- Depends on what data you have!
- Molecular data suggests a closer relationship between whales and hippos…

Whale Evolution: Whales and Hippos share common ancestor



